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Biomedical subjects

B S Cowen

Publications and source records attributed to B S Cowen.

At least 19 recordsLinked to original sources
PubMed1995

Changes in pulmonary arterial and femoral arterial blood pressure upon acute exposure to hypobaric hypoxia in broiler chickens.

An experiment was conducted to investigate the pulmonary arterial and femoral arterial pressure responses to acute hypobaric hypoxia. Twenty-four, 7-wk-old Hubbard x Hubbard male chickens were lightly anesthetized and catheters were introduced into the right femoral artery and the pulmonary artery. The birds were then placed in a hypobaric chamber, and blood pressure responses were monitored during acute (15 min) exposures to simulated altitudes of 2,000 and 4,000 m. The pulmonary artery pressure increased .7 and 4% during the first and second exposures to a simulated altitude of 2,000 m, whereas the femoral artery pressure decreased 6 and 8% during exposures to this altitude. The pulmonary artery pressure increased 7% on the first exposure and 23% (P < .05) on the second exposure to a simulated altitude of 4,000 m. The femoral arterial pressure decreased (P < .05) on both exposures to this altitude (29 and 24%, respectively). The initial femoral and pulmonary artery pressures and changes in these pressures upon exposure to hypobaric hypoxia were not consistently correlated with the characteristics of the electrocardiogram, packed cell volume, body weight, or the right:total ventricular weight ratio. These results indicate that acute hypobaric hypoxia elicits a hypotensive response in the systemic arterial circulation and a hypertensive response in the pulmonary arterial circulation of broiler chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Altitude↗
PubMed1995

Influenza A viruses isolated from waterfowl in two wildlife management areas of Pennsylvania.

A survey was conducted at two wildlife management areas of Pennsylvania (USA) to evaluate an antigen capture enzyme-linked immunosorbent assay (AC-ELISA) for the detection of avian influenza viruses (AIV) in cloacal swabs from waterfowl and to determine the influenza A virus subtypes and the distribution of these viruses among waterfowl. We collected 330 cloacal swabs from hunter-killed waterfowl in the fall of 1990 and from cage-captured waterfowl in the summer of 1991. Thirty-one hemagglutinating agents were isolated by chicken embryo inoculation (CEI) of which 27 were influenza A viruses and four Newcastle disease viruses (NDV). The prevalence of AIV infection was 8.2%. Compared to CEI, AC-ELISA was only 15% sensitive and 61% specific. Based on the distribution of AIV by species of waterfowl, mallards (Anas platyrhynchos) and American wigeons (Anas americana) were at equal risk of AIV infection even though most of the AIV isolates came from mallards. Although significant crude effects of sampling site and season on AIV recovery could be established, juvenile age was identified as the primary risk factor of AIV recovery. Twelve AIV subtypes were identified by hemagglutination inhibition (HI) and neuraminidase inhibition (NI) tests. The most prevalent subytpes were H4N8 and H6N8. We concluded that AC-ELISA was not useful for the detection of AIV in cloacal swabs from waterfowl and that CEI, HI, and NI tests remain as the method of choice for AIV screening in waterfowl. Based on the results AIV infected preferentially the young which represent the high risk group in waterfowl populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

Order of exposure to high dietary calcium and gray strain infectious bronchitis virus alters renal function and the incidence of urolithiasis.

Experiments were designed to determine if Gray strain infectious bronchitis virus (IBV) infection increases the incidence of urolithiasis type kidney damage when the urine is already high in Ca and relatively alkaline due to a high Ca-low available P diet (i.e., layer ration). In addition, experiments were conducted to determine the effects of Gray strain IBV on pullet renal function of 6 and 14-wk-old pullets at 2, 5, and 10 days postinoculation (PI). Blood gas parameters were measured to determine the mechanism by which layer ration decreases hydrogen ion concentration [( H+]). Urine flow rate, glomerular filtration rate, electrolyte excretion (Na, K, Ca, P), free water clearance, urine osmolality, urine [H+], and renal plasma flow (para-aminohippuric clearance) were measured to assess renal function. Gray strain IBV increased urine [H+] and decreased renal plasma flow in 6-wk-old pullets, and induced a diuresis in 14-wk-old pullets between 5 and 10 days PI. The layer ration increased Ca excretion and induced a metabolic alkalosis, thus decreasing urine [H+] and causing urolith formation. Feeding layer ration followed by Gray strain IBV infection had an additive effect on the incidence of urolithiasis and gross kidney damage. Gray strain IBV infection 8 wk prior to feeding layer ration did not induce urolithiasis. The results suggest that the additive effect of Gray strain IBV on the incidence of urolithiasis is probably due to tubular damage rather than direct changes in renal function parameters.

Acid-Base Equilibrium↗
PubMed1988

Effect of Gray strain infectious bronchitis virus and high dietary calcium on renal function of Single Comb White Leghorn pullets at 6, 10, and 18 weeks of age.

Experiments were designed to evaluate the effects of Gray strain infectious bronchitis virus (IBV) and high dietary calcium (Ca), alone and in combination, on renal function in pullets. Eight hundred female Single Comb White Leghorn chicks were raised on starter ration. Five hundred chicks were inoculated intravenously with Gray strain IBV at 4 wk of age; the remaining chicks were not exposed to IBV. At 6 wk of age, IBV-inoculated and uninoculated chicks were randomly divided into two diet treatment groups. Half the chicks were fed commercial grower ration (approximately 1.0% Ca, .6% available P) and half were fed commercial layer ration (approximately 3.25% Ca, .5% available P). Birds remained on their respective diets until 18 wk of age. Kidney function studies were conducted on anesthetized birds at 6 wk of age prior to initiation of the diet treatments, at 10 wk of age, and at 18 wk of age. The layer ration increased Ca excretion, decreased inorganic phosphate excretion, and decreased urine hydrogen ion concentration in 10-wk-old pullets in comparison with the grower ration. These diet effects on kidney function were attenuated when the pullets reached 18 wk of age. The layer ration also caused an 11.5% incidence of urolithiasis, and significantly increased kidney asymmetry in 18-wk-old pullets relative to the effects of the grower ration. Gray strain IBV exposure significantly increased kidney asymmetry in 18-wk-old pullets, but had no gross effect on kidney function clearly related to the etiology of urolithiasis. Gray strain IBV did not enhance the incidence of urolithiasis in any of the age groups.

Age Factors↗
PubMed1988

Effect of dietary acidification and alkalinization on urolith formation and renal function in Single Comb White Leghorn laying hens.

One of the major causes of mortality in poultry is urolithiasis. Although two of the major causes of urolithiasis have been defined, active and preventative treatments for this disease have not been extensively field tested. Previous research demonstrated that a diet acidified with NH4Cl was effective in preventing the formation of uroliths in 16-wk-old pullets. In the present study, experiments were designed to evaluate the effects of dietary acidification and alkalinization on preformed uroliths in mature laying hens. Urolithiasis was induced by feeding excess dietary Ca (in commercial layer ration) during pullet growout (6 to 18 wk of age) and during the early laying period (18 to 32 wk of age). At 32 wk of age birds were randomly divided into three diet treatment groups: a normal layer ration group, an acidified layer ration group (1% NH4Cl added); and an alkalinized layer ration group (1% NaHCO3 added). Each group received the respective diets until 52 wk of age, when the experiment was terminated. Blood gas analysis at 44 wk of age demonstrated that hens fed the acidified diet had significantly higher blood H+ concentrations, lower blood bicarbonate concentrations, and lower total blood carbon dioxide levels than hens fed the alkalinized layer ration. At 52 wk of age, hens fed the acidified layer ration had higher urinary H+ concentrations, higher blood H+ concentrations, and lower blood HCO3 and total CO2 concentrations than hens fed the normal and alkalinized layer rations. The acidified layer ration group had no uroliths present in their ureters (0% urolithiasis), whereas the normal and alkalinized layer ration groups had 8.3 and 13.1% incidences of urolithiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonium Chloride↗
PubMed1987

Effect of dietary acidification on kidney damage induced in immature chickens by excess calcium and infectious bronchitis virus.

Experiments were designed to evaluate the effect of dietary acidification on the development of kidney lesions induced by excess dietary calcium (Ca) and Gray strain infectious bronchitis virus (IBV). Specific pathogen-free (SPF) chicks and SPF chicks inoculated with Gray strain IBV were fed one of three diets: a commercial pullet grower ration (1% Ca); a commercial layer ration (3.25% Ca); or layer ration plus .5% ammonium chloride (acidified layer ration). Gray strain IBV significantly reduced total kidney weights in males, reduced total kidney weight as a percentage of body weight in males, increased the number of gross kidney lesions, and decreased the number of filtering nephrons when compared with uninoculated birds when both groups were fed the grower ration. The layer ration induced a 60% incidence of kidney lesions, caused a significant increase in kidney weight asymmetry ratios, and caused a 25% reduction in the number of filtering nephrons. Acidifying the layer ration significantly reduced the incidence of gross kidney lesions and reduced kidney weight asymmetry ratios, but did not prevent Ca-induced reductions in filtering nephrons.

Acidosis↗
PubMed1985

Induction of urolithiasis in single comb white Leghorn pullets: effect on glomerular number.

Urolithiasis was induced in an experimental group of Single Comb White Leghorn pullets by feeding them layer ration and exposing them to nephrotrophic Gray strain infectious bronchitis virus (IBV). Gray strain IBV was recovered from kidney and cloacal swabs for up to 26 days after exposure to the virus. Control pullets fed pullet grower ration and not exposed to Gray strain IBV did not develop urolithiasis. The experimental design did not allow differentiation between the roles of layer ration and IBV in triggering urolithiasis. Urolithiasis was associated with asymmetry in left vs. right kidney weight comparisons for individual pullets. Pullets from the urolithiasis group had 43,800 +/- 4,500 glomeruli/gram kidney weight, whereas control pullets had 68,770 +/- 3,500 glomeruli/gram kidney weight. This difference was significant (P less than .01). Total kidney weights did not differ significantly when the experimental and control pullets were compared. Comparisons of glomeruli size distributions indicated that the number of intermediate sized glomeruli (.15 to .22 mm in circumference) was significantly reduced in pullets from the urolithiasis treatment group. These observations indicate that a significant reduction in nephron number can be masked by compensatory hypertrophy of the remaining kidney tissue in pullets with urolithiasis.

Animals↗
PubMed1985

Urolithiasis in pullets and laying hens: role of dietary calcium and phosphorus.

A study was conducted to test the independent and combined effects of high dietary calcium and low available phosphorus on the incidence of urolithiasis in pullets and laying hens. One thousand Single Comb White Leghorn pullets were divided into four diet treatment groups beginning at 50 days of age. A normal calcium (1%), normal available phosphorus (.6%) diet (NCNP) was fed to control pullets. Other pullet groups were fed a high calcium (3.25%), normal available phosphorus (.6%) diet (HCNP), a normal calcium (1%), low available phosphorus (.4%) diet (NCLP), or a high calcium (3.25%), low available phosphorus (.4%) diet (HCLP). At 18 weeks of age, 368 pullets were necropsied. One percent of the HCNP group and 14% of the HCLP group developed urolithiasis. Urolithiasis was not found in pullets raised on the NCNP and NCLP diets. The remaining pullets were transferred to laying cages and were fed a commercial layer ration until they were 51 weeks old. None of the hens raised on the NCNP diet, 12% of the hens raised on the HCNP diet, 2% of the hens raised on the NCLP diet, and 14% of the hens raised on the HCLP diet had urolithiasis. Renal function studies were performed on 18-week-old pullets and 51-week-old hens. Pullets raised on the HCLP diet had significantly higher urine pH, significantly lower fractional inorganic phosphate excretion, and significantly higher fractional calcium excretion when compared with pullets raised on the other diet treatments. The profound effect of the HCLP diet on renal calcium and phosphorus excretion in pullets was not retained in the hens.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMedDate not supplied

Characterization of a new infectious bronchitis virus isolate. III. Cell-culture adaptation of Clark 333.

The Clark 333 strain of infectious bronchitis virus (IBV) was substantially resistant to primary chicken cell-culture adaptation. More than 40 serial embryo passages were required before the virus would produce cytopathic alterations upon cell-culture inoculation. The cytopathic effect was characteristic of the effect of reported for IBV. Adaptation was not accomplished by alternating serial passages in embryo and cell-cultured systems. A careful monitoring of cell-culture fluid infectivity by embryo inoculation was found to be essential because absence of adaptation is accompanied by a loss in virus titer (3 to 5 serial passages). Helpful additional aids were immunofluorescence and cytopathology.

Animals↗
PubMedDate not supplied

Adenoviruses of chickens: serologic groups.

By literature review and experimental studies, 57 adenovirus isolants from chickens were grouped into 10 distinct serotypes. In plaque-reduction tests, 20 antibody units were reacted with 32-320 plaque-forming units of virus. Viruses that were neutralized (80% or greater reduction in titer) by a given serum were considered to belong to that serotype. Used to distinguish among serotypes were their antisera. One-way neutralization occurred in only two instances; in both cases it was traced to contamination of the virus inocula used to induce specific antiserum. Recloning corrected the problem. Of the 10 serotypes described, all are known to exist in the United States, 7 were found in Northern Ireland, and at least 6 have been shown to occur in Japan.

Adenoviridae↗
PubMedDate not supplied

Experimental egg-transmission of avian reovirus.

Two experiments with an avian reovirus (FDO isolant), serologically identical to the Fahey-Crawley and WVU 2937 isolants, provided conclusive proof that egg-transmission can occur. In the first experiment, 4-day-old chicken embryos were inoculated into the yolk sac with serial dilutions of virus and subsequently hatched. High virus doses killed all embryos, whereas low doses (14 or less plaque-forming units) allowed some embryos to hatch normally although infected. In the second experiment, virus was administered by the nasal, esophageal, and tracheal routes to twenty 15-month-old breeders. Eggs from -6 to 21 days and 58 to 64 days postinoculation were incubated. Three newly hatched chicks from eggs laid on successive days (17, 18, and 19 days postinoculation) and one infertile egg (61 days postinoculation) were found infected. Active infection, as judged by virus isolations from cloacal swabs, was over by the 17th day postinoculation.

Administration, Intranasal↗
PubMedDate not supplied

Localization of avian reovirus (FDO isolant) in tissues of mature chickens.

Mature hens were exposed to a reovirus (FDO isolant) serologically related to the viral arthritis agent. Examination of 23 tissues from the respiratory, alimentary, and reproductive tracts and tendons from the hock joint revealed widespread infection 4 days after inoculation via the respiratory and alimentary tracts. By 14-15 days, infection had largely subsided but was still detectable in the tendons, oviduct, and alimentary tract of some birds. No infection was found at 30 days. Virus isolation attempts in chick kidney cultures were more reliable than fluorescent-antibody tests for detecting infection. None of 156 chicks hatched from eggs laid between 12 and 33 days postinoculation were infected.

Administration, Intranasal↗
PubMedDate not supplied

Serotyping of avian infectious bronchitis viruses by the virus-neutralization test.

The antigenic relationships of 12 strains of infectious bronchitis virus (IBV) were evaluated by a virus-neutralization procedure similar to that used in typing human rhinoviruses. Such a procedure consists of reciprocal neutralization tests performed by reacting 32-320 EID50 or plaque-forming units of virus with 20 antibody units of antiserum. Eight serologic groups were identified by chicken embryo assay, and 4 by plaque-reduction (90%). In general, serologic groupings were not distinct but reflected numerous intergroup relationships. The contrasting results exhibited by indicator systems are viewed as differences in the accuracy of the methods employed. It is suggested that before an IBV classification scheme can be proposed, agreement must be reached on the most suitable indicator system, techniques must be standardized, and reference viruses and antisera distributed to several institutions for comparison testing. In addition, cross-protection studies are needed to determine the importance of IBV serotypes and/or variants on vaccine efficacy.

Animals↗
PubMedDate not supplied

Use of a hypobaric chamber as a model system for investigating ascites in broilers.

In a series of experiments, broilers were reared at simulated altitudes of 3000, 3500, and 5000 meters utilizing a hypobaric chamber. The purpose was to evaluate the chamber as a model for ascites syndrome and to further study the pathophysiology of this disease. Results show that this model can effectively reproduce the disease as it is seen in the field. Birds reared at the simulated altitude of 5000 meters had a statistically significant increase in EKG amplitude, packed cell volume, and heart-to-body-weight and lung-to-body-weight ratios when compared with controls reared at 366 meters. Additionally, there was a trend for birds dying of ascites to have larger-amplitude EKGs than survivors when reared at 5000 meters.

Altitude↗
PubMedDate not supplied

An infectious bronchitis virus isolated from chickens experiencing a urolithiasis outbreak. I. In vitro characterization studies.

An infectious bronchitis virus (IBV) strain isolated from commercial layers experiencing urolithiasis was 50-100 nm in size and possessed widely spaced, club-shaped surface projections. It was sensitive to lipid solvents and exhibited responses characteristic of IBV when exposed to heat, divalent cations, and trypsin. Reciprocal virus-neutralization tests demonstrated it to be closely related to Gray, JMK, Delaware 2868, and Delaware 2897 strains of IBV.

Animals↗
PubMedDate not supplied

Chicken embryo propagation of type I avian adenoviruses.

Forty-two clone-purified, cell-culture-propagated type I avian adenoviruses (AAV) representing 11 serotypes and two intermediate strains were evaluated for virus replication (evidenced by embryo death and lesions) resulting from the inoculation of specific-pathogen-free chicken embryos via the chorioallantoic sac or yolk sac. Commonly observed embryonic changes were death, stunting and curling, hepatitis, splenomegaly, congestion and hemorrhage of body parts, and urate formation in the kidneys. Basophilic or eosinophilic intranuclear inclusion bodies characteristic of fowl adenoviruses were observed in hepatocytes. The magnitude and relative uniformity of intra- and interserotypic embryo mortality, gross lesions, and virus titers was greater in embryos inoculated via the yolk sac. This work identifies the yolk sac as a practical and sensitive chicken embryo inoculation route for poultry diagnosticians to employ. It is suggested that the yolk sac may be a reliable alternative to cell culture for the successful isolation of all type I avian adenoviruses.

Adenoviridae↗